Atmospheric particulate matter (PM) samples were collected in Riyadh, Saudi Arabia, to assess air quality, quantify, heavy metal concentrations, and evaluate related ecological and health risks. This study’s uniqueness stems from its focused and detailed analysis of PM pollution in Riyadh, including an extensive assessment of heavy metal concentrations across different PM sizes by applying diverse pollution and health indices. This brings to light critical health and ecological issues and provides foundation for targeted pollution control efforts in the region. The study focused on two PM size fractions, PM_2.5 and PM₁₀ and analyzed the presence of heavy metals, including iron (Fe), nickel (Ni), chromium (Cr), zinc (Zn), cobalt (Co), copper (Cu), silver (Ag), arsenic (As), cadmium (Cd), and lead (Pb), using inductively coupled plasma emission spectrometry. Results showed significantly higher levels of PM₁₀ (223.12 ± 66.12 µg/m³) compared to PM_2.5 (35.49 ± 9.63 µg/m³), suggesting that local dust is likely a primary source. Air quality varied from moderate to unhealthy, with PM₁₀ posing substantial risks. Heavy metal concentrations in PM_2.5 followed the order Fe (13.14 ± 11.66 ng/m³) > As (2.87 ± 2.08 ng/m³) > Cu (0.71 ± 0.51 ng/m³) > Zn (0.66 ± 0.46 ng/m³) > Cr 0.50 ± 0.23 ng/m³) > Pb (0.14 ± 0.10 ng/m³) > Ni (0.03 ± 0.04 ng/m³) > Cd (0.004 ± 0.002 ng/m³) > Ag (0.003 ± 0.003 ng/m³) > Co (0.002 ± 0.004 ng/m³). In PM10, they followed the order Fe (743.18 ± 593.91 ng/m³) > As (20.12 ± 13.03 ng/m³) > Cu (10.97 ± 4.66 ng/m³) > Zn (9.06 ± 5.50 ng/m³) > Cr (37.5 ± 2.70 ng/m³) > Ni (1.72 ± 01.54 ng/m³) > Pb (1.11 ± 0.64 ng/m³) > Co (0.25 ± 0.28 ng/m³) > Ag (0.10 ± 0.26 ng/m³) > Cd (0.04 ± 0.02 ng/m³). Enrichment factor analysis revealed elevated levels for the metals Cu, Zn, As, Ag, Cd, and Pb. Pollution indices indicated various contamination levels, with Ag and As showing particularly high contamination and ecological risks. The study highlighted significant health concerns, especially from As, which poses a substantial long-term carcinogenic threat. The findings emphasize the urgent need to reduce hazardous metal levels in Riyadh’s air, especially with high child exposure.

Background: Polycyclic aromatic hydrocarbons (PAHs) in atmospheric particulate matter (PM) are high in Saudi cities due to industry and traffic, often exceeding safety limits. This study assesses PM_2.5 and PM₁₀ and health risks in Riyadh’s desert environment. Method: High-purity chemicals and PAH standards were used. Air samples were collected at King Saud University, extracted, cleaned, and analyzed by GC-MS. QA/QC ensured accuracy, with RSDs of 4.6–7.9%. Results: Seasonal temperature shifts in Riyadh influence PM and PAH levels. Higher summer temperatures raise PM/PAH, posing health risks, especially via inhalation. Winter favors PAH accumulation on particles. Conclusions: Seasonal temperature shifts significantly affect PM_2.5, PM₁₀, and PAH levels in Riyadh, with summer posing the highest health risks. Inhalation is the main exposure route, especially for PM_2.5.

Surface sediment samples from Al-Qahma lagoon in the southern part and Al-Wajh lagoon in the northern part of the Red Sea coast of Saudi Arabia were collected by a Van Veen grab sampler to determine the characteristics, distribution, and sources of aliphatic and cyclic hydrocarbons. The total extractable organic matter (TEOM) was extracted with a dichloromethane/methanol mixture after drying and sieving the sediments and identified by gas chromatography–mass spectrometry. The TEOM comprised n-alkanes (302.6 ± 446.7 ng·g⁻¹ and 64 ± 50 ng·g⁻¹), hopanes (29.8 ± 132.3 ng·g⁻¹ and 1.0 ± 2.5 ng·g⁻¹), steranes (0.0 and traces), n-alkanoic acids (745.8 ± 799.6 ng·g⁻¹ and 120.7 ± 92.0 ng·g⁻¹), n-alkanols (457.4 ± 1085.6 ng·g⁻¹ and 49.7 ± 32.3 ng·g⁻¹), polycyclic aromatic hydrocarbons (PAHs) (54.5 ± 96.8 ng·g⁻¹ and 7.8 ± 8.5 ng·g⁻¹), and phthalates (185.3 ± 169.9 ng·g⁻¹ and 67.4 ± 70.4 ng·g⁻¹) in the Al-Qahma and Al-Wajh lagoon sediments, respectively. The percentages of the various sources relative to total aliphatic and cyclic hydrocarbon concentrations were 6.9 ± 6% for terrestrial plants, 53.7 ± 19% for algae, 10 ± 2% for microbial, 16 ± 12% for petroleum, and 13.4 ± 7 for plasticizer inputs in Al-Qahma lagoon. In Al-Wajh lagoon, they were 9.7 ± 4% for terrestrial plants, 30.8 ± 14% for algae, 25.2 ± 5% for bacteria, 11.2 ± 3% for petroleum, and 23.1 ± 11% for plasticizers.